Joseph w



(No'Moael.)

J. W. THOMPSON. EGUENTRIG POR STEAM ENGINES.

Patented Oct. 17, 1882.

VCR

Inven 01' Witnesses UNITED STATESl PATENT Ormea.

JOSEPH W. THOMFSON, OF SALEM, OHIO, ASSIGNOR OF ONE-HALF TO THE BUOKEYE ENGNE COMPANY, OF SAME PLAGE.

ECCENTRIC FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent No. 265,994, dated October 17', 1 882.

(No model.)

To all whom it may concern:

Be it known that I, JOSEPH W. THOMPSON, of Salem, in the county of Columbiana and y State of Ohio, have invented certain new and useful Improvements in Eccentrics for Steam- Engines, of which improvements the following is a specification.

My invention relates to an adjustable eccentric mounted loosely upon its shaft and varied ro in position angularly about the center thereof by a governor or regulator, for the purpose of maintaining uniformity of speed of an engine under vari-ationsof load and steam-pressure by causing the valve which it actuates to cut I5 off steam earlier or later in the stroke in correspondence with said variations. Foran illustration and description of such device and its operative relation to the' cut-oli' valve of an automatic cut-ofi1 engine reference may be had 2o to Reissued Letters latentof the United States Nos.8,432,8,433, and 8,434, granted and issued to myseltl and the Buckeye Engine Oompany (as my assignee) under date of September 24, 1878.

z5 The object of my present invention is to promote the normal. and accurate location of an eccentric ofthe above class for each different degree of cut-oli' that may be required to be effected in the operation ofthe engine by eliminating, as far as may be, forces tending to disturb an equilibrium between the centrifugal and centripetal forces acting upon the regulator.

To this end my improvements consist in the combination of an adjustable eccentric and a counter-weight or'balance acting upon said eccentric in opposition to the action induced by the steam-pressure upon the stem of the valve operated by saideocentric; also, in the combi- 40 nation of an adjustable eccentric, balanced as set forth, with a cut-oli' valve and an intermediate connection for operating said valve. The improvements claimed are hereinafter more fully set forth.

ln the accompanying drawings, Figure l is a side view, partly in section, of so much of a steam-engine as is necessary to exhibit the application of my invention. Figs. 2, 3, and 4 are diagrams illustrating dierent'positions of 5o the eccentric in'the Vrevolution of the shaft;

and Fig. 5, a view partly in elevation and partly in section of a split or divided eccentric embodying my invention.

lhe eccentric A is-titted freely upon the main or crank shaft A ofthe engine, so as to be movable thereon angulaily to the crank, such movement being imparted by a governor or regulator of any suitable and preferred construction, to which the eccentric A is connected, as described and shown in Reissues Nos. 6: 8,432 and 8,433 aforesaid. The cut-oft' valve B, which consists of two plates united by rods or bars D, works. within a box or chambered main distribution-valve, B', having ports b adjacent to each of its ends, which ports are opened and-closed bythe cut-oli valve B in its traverse, the earlier or later closure of each of them relatively to the traverse of the piston being determined by the variations ofthe position of the eccentric induced by the gov- 7o ernor. The stem b2 of the' cut-oli' valve B passes out through a stuiiing-box, b3, on the stem b4 of the main valve B', and is connected, in this instance through the intermediation ot' a rock-shaft, C, and arms c c', to the rod a of 75 the eccentric A. The details of the valve construction, which do not, however, per sc, constitute part of my present invention, are fully set forth in Reissue i\o. 8,4254 aforesaid. To facilitate the movement of the eccentric by 8o the governor, a counter-weight, D, sutlicient to balance the weight of the eccentric and so much of the Weight ot' the rod as is not supported by the rocker-arm, is connected to the eccentric A, said weight projecting radially from the eccentric in the line of its radius ot eccentricity, and on the side adjacent to the center of its shaft opening or bore.

It will be seen that the pressure ofthe steam in which the cut-oli' valve Works tends con- 9o stantly to move said valve outwardly in the direction of the crank-shaft A with a force equal to the transverse area of the cut-oftvalve stein multiplied by the 'pressure of steam per square inch,and such action, which proportion- 9 5 ately interferes with close and accurate regulation bythe governor, has prior to my inven-v tion been neglected and uuprovided for. To counteract the disturbinginliuence induced by said unbalanced steam-pressure upon the outroo olf-valve stein, and thereby to relieve the governor from the abnormal action thereof, I attach to the adjustable eccentric A a counter- \veight or gravity-balance, E, connected to a stein, e, and so located as to act equivalently iu effect, as nearly as may be, and oppositely in direction to the pressure exertedY by the steam upon the area of the cut-oE-valve stein b2, the stem ofsaid counter-weight consequently projecting radially from the eccentric at an angle approximating a right angle with the line of projection of the stem d of the main counter-weight 1), the variation from a right angle being due to and corresponding with the inclination of the eccentric-rod.

As shown in Figs. l and 3, the eccentric A is on its dead-centers-that is to say, in positions corresponding to the termination of the traverse of the cut-off valve which it act uatesand inasmuch as when in said positions the steam-pressure upon the stem is not effective as a disturbing agent upon the equilibrium of the regulator, the counter-weight E then stands in vertical position and exerts no effect upon the regulator. When the eccentric is in the positions shown in F1gs.2 and 4 the steam-pressure upon the valve-stem and the gravity of the counter-weight each act with maximum effectivenessand in opposite directions, respectively, upon the eccentric, and theseforces may obviously be made to exactly balance eachother at any determined pressure, which in practice should be fixed at or slightly above the-average working pressure. Where the cu t-off valve is worked directly by the eccentric-that is, without the interposition of a rock-shaft-the counter-weight E should project from the eccentric in opposite direction to that shown, and as in such case the eccentric-rod and valvestern would be substantially in line, its line of projection should be at right angles to that of the main counter-weight D.

1f desired, a single counter-Weight, F, Figs. 4 and 5, may be employed as the resultant of the effects of the two separate counter-weights l) and E and as an equivalent in substitution thereof. In such case the location ofsaid coun- 1er-weight F Would beupon the diagonal ofthe parallelogram formed by two lines drawn from the center of the shaft to the centers of the counter-weights D and E and two lines respectively parallel to said first-named lines, and the center of the counter-weight F would either coy incide with the point of intersection of said two last-named lines or be Within or Without said point, according as the substituted tounter-Weight F is of equal or of different amount to the counter-weight D. The single counter- Weight F, shown in Fig.5 as applied to asplit or divided eccentric, is secured thereto by the engagement of one of the bolts a', which connect the two halves of the eccentric, with the stemfot'thccounter-Weght. Theemployment of a single counter-Weight is advantageous in point of simplicity and economy; but I prefer the use of separate counter-weights to balance the Weight ofthe eccentric and the steam-pressure on the stem, respectively, as rst hereinabove described, as such construction embodies the capacity of adjusting the effect ofthe pressure counterweight in correspondence with varying working pressures of steam independently of the eccentric-balance, which should necessarily remain constant. The adjustment referred to is here shown as provided for by connecting the pressure counter-weightE to its stem e by a set-screw, e', so that the Weight maybe moved toward or from the center ofthe shalt and 'Xed in any desired position upon its stem.

I claim as my invention and desire to secure by Letters Patent- 1. The combination, substantially as set forth, ot' an adjustable eccentric and a balance or counter-weight secured thereto in such position as to exert its gravity upon the eccentric ina reverse directionto the action of the steampressure upon the stem of the valve actuated by said eccentric.

2. rlhe combination, substantially as set forth, of an adjustable eccentric, a balance or counter-weight acting in reverse direction to the preponderance ot" Weight of the eccentric upon the shaft, and a counter-Weight acting in reverse direction to the pressure of steam upon the stem of the valve actuated by the eccentric.

3. The combination, substantially as set forth, of an adjustable eccentric, a valve actuated thereby through an intermediate connection, and a balance or counter-Weight acting upon the eccentric in reverse direction to the pressure of steam upon the stem of said valve.

JOSEPH W. THOMPSON.

Witnesses:

PETER AMBLER, ALBERT CAMERON. 

